The Williams Group's analyses of wind/compressed air energy storage (wind/CAES) systems have
focused on mitigating the variability of wind and enhancing utilization of the transmission lines
needed to access remote, high-quality wind resources by coupling wind farms to compressed air
energy storage systems. During 2005-2008 this research was led by Samir Succar under Williams'
supervision.

A milestone in this research was the completion of a major PEI report on CAES: Compressed Air
Energy Storage: Theory, Resources, and Applications for Wind Power, which was released in April
2008. That report focuses on the geologic requirements for underground air storage, the geographic
distribution of wind and storage resources, and the prospective economics of wind/CAES systems
relative to coal IGCC without and with CCS.

The central findings of this report are that while additional data are needed to fully assess total
storage capacity available in North America, geologies suitable for CAES are widespread and well
correlated with the location of high-quality wind resources. This correlation is very auspicious for a
low-carbon US energy future because exploitable high-quality wind resources in the US could
theoretically satisfy the entire US electricity demand—if ways can be found to deal cost-effectively
with the intermittency and remoteness challenges, which CAES systems might enable if sufficient
suitable storage capacity can be identified and exploited.

Finally, the report finds that wind/CAES systems prospectively offer attractive economics for
generating low-carbon power under the conditions characterizing a serious carbon-mitigation policy.
First, baseload wind/CAES systems would become cost competitive (on the basis of levelized
electricity costs) with coal IGCC at carbon price levels needed to make CCS economic for such
systems. Second, once built, wind/CAES systems would be highly competitive in economic dispatch
competition relative to other baseload electric power technologies.

The release of this report and subsequent completion by Succar of his PhD dissertation in Electrical
Engineering on this topic conclude a major portion of this work. In September Succar joined the
Natural Resources Defense Council in New York, where he is focusing on issues related to the
integration of renewable with conventional energy systems. But Succar will continue as a visiting
research scholar at PEI and will continue collaborations with Williams and others. Succar and
Williams plan to write several papers for peer-reviewed journals based on the CAES report and
Succar's thesis. In addition, during the coming year, Kreutz, Williams and possibly also Succar will
pursue an analysis exploring the prospects for displacing existing coal-intensive power with
decarbonized power in economic dispatch competition by adding to electric grids both coal/biomass
polygeneration with CCS and wind/CAES systems.